Reanalysis of crystal field parameter datasets for rare-earth ions at low symmetry sites: Nd³⁺ in NdGaO3 and Pr³⁺ in PrGaO3

Authors:

• Czesław Zygmunt Rudowicz,
• J. Qin

Abstract

This study deals with the compatibility and reliability of the crystal field parameter (CFP) datasets for Nd³⁺ (Pr³⁺) ions at low symmetry sites in NdGaO₃ (PrGaO₃), which exemplify a number of apparently disparate and/or incompatible CFP datasets revealed by our recent literature survey. These considerations clarify three important aspects: (1) the definitions of the axis systems adopted in the pertinent CF studies; (2) the relevant coordination factors involved in the point charge model calculations; and (3) the multiplicative factors missing in some CFP's, e.g., those obtained by inelastic neutron scattering technique. Based on standardization theory, the reanalysis of the CFP's for Nd³⁺ in NdGaO₃ and Pr³⁺ in PrGaO₃ enables to resolve the discrepancies identified in the previous studies. A survey of CFP datasets for Nd³⁺ ions in other structurally similar crystals is carried out for a meaningful comparison. Correlations between the physically equivalent CFP datasets for Nd³⁺ ions in NdGaO₃ obtained by transformations of the nominal axis system are also considered. This work lays grounds for similar CF studies of rare-earth ions at low symmetry sites. © 2004 Elsevier B.V. All rights reserved.